Press unloader

ABSTRACT

A press unloader having a reciprocating tray for receiving workpieces ejected from an upper die in a press. The tray is shifted to the work-receiving position at a rate controlled by the upward rate of the press ram and is rapidly retracted at a rate independent of the rate of the press ram so that the next workpiece may be conveniently loaded into the press.

United States Patent Wallis [is] I 3,653,293

[451 Apr. 4, 1972 [54] PRESS UNLOADER I [72] Inventor: Bernard J.Wallis, 25200 Trowbridge Avenue, Dearborn, Mich. 48124 [22] Filed: Aug.7, 1970 21 App1.No.: 62,004

[51] Int. Cl ..B26d 7/06 [58] Field oiSearch .83/81, 82, 157; 72/361;

[56] References Cited I UNITED STATES PATENTS 2,377,262 5/1945 OLeary..83/81 3,148,571 9/1964 Wallis ..83/82 3,349,602 10/1967 Nelson..83/157X Primary Examiner-Andrew R. J uhasz Assistant Examiner-David R.Melton Attorney-Bames, Kisselle, Raisch & Choate [57] ABSTRACT A pressunloader having a reciprocating tray for receiving workpieces ejectedfrom an upper die in a press. The tray is shifted to the work-receivingposition at a rate controlled by the upward rate of the press ram and israpidly retracted at a rate independent of the rate of the press ram sothat the next workpiece may be conveniently loaded into the press.

12 Claims, 6 Drawing Figures PATENTEDAPR 4 I972 sum 1 BF 3 AdjustableDeloq Valve FIG.@

ATTORNEYS PATENTEDAPR 4 I972 3, 653 293 SHEET 2 BF 3 1;; \/l:.\"l' JR.BERNARD J. WALLIS ATTORNEYS PATENTEDAPR 4 1972 SHEET 3 OF 3 INVENTOR.

BERNARD .J. WALLIS ATTORNEYS PRESS UNLOADER The present inventionrelates to material handling equipment and more particularly to a pressunloader for mechani' cally unloading stampings or the like from betweendie elements in a press or similar machine without interrupting theoperation of the machine.

The present invention is of particular utility in the unloading of apunch press in which the formed article is elevated with the upper dieelement as the die opens and is then ejected downwardly from the upperdie element by knock-out pins which operate at the terminal portion ofthe upstroke of the press. One commonly used form of press unloaderincludes a tray arranged to reciprocate to a work-receiving positiondisposed between the separated upper and lower dies in the press so asto receive workpieces ejected from the upper die when the ram reachesthe upper end of its stroke. Such an arrangement is illustrated in myprior U.S. Pat. No. 3,148,571, issued Sept. 15, 1964. With such anarrangement the reciprocation of the tray is controlled by the verticalmovement of the ram. When the ram moves upwardly the tray is projectedto the work-receiving position, and when the ram moves downwardly thetray is retracted to an out-of-the-way position. While such anarrangement is satisfactory in many applications, it presents a problemwhen the press is loaded manually. This problem arises from the factthat with an arrangement such as shown in my prior patent thework-receiving tray is not completely retracted until the press ramapproaches the lower end of its stroke. Thus, it is difficult to loadworkpieces into the press while the tray is being retracted.

The object of the present invention is to provide a press unloader whichenables workpieces to be conveniently and rapidly loaded into the presswithout interference from the press unloader.

More specifically, it is an object of the present invention to provide apress unloader of the reciprocating tray type wherein the tray isretracted rapidly from the work-receiving position while the ram is atthe upper end of its stroke so that after a workpiece is ejected fromthe upper die the next workpiece can be loaded into the press withoutinterference from the work-receiving tray. In the drawings:

FIG. 1 is a fragmentary elevational view of a press and press unloaderof the present invention with the parts illustrated in the positionsassumed when the press ram is at the upper end of its stroke.

FIG. 2 is a view similar to FIG. 1 and showing the position of thevarious parts when the press ram is at the lower end of its stroke.

FIG. 3 is a sectional view taken along line 33 in FIG. 2

FIG. 4 is a sectional view taken along line 4-4 in FIG. 3.

FIG. 5 is a sectional view taken a long line 5-5 in FIG. 4.

FIG. 6 is a schematic diagram of the fluid control circuit.

Referring to the drawings, a punch press is generally indicated at 10.The press includes a base 12 and a ram 14. Ram 14 is guided for verticalreciprocating movement by means of guides 16. In use an upper die 18 ismounted on ram 14 and a lower die 20 is mounted on the platen 22 of thepress.

The press unloader of this invention is generally designated 24 and ismounted at one side of base 12 by a bracket 26. Press unloader 24generally comprises a drive assembly 28 and a tray assembly 30. Each ofthese assemblies is mounted on a base plate 32 in spaced-apart relation(FIG. 3). Drive assembly 28 includes a vertically extending gear rack 34coupled at its upper end to an extension 36. Extension 36 is providedwith a bumper element 38 at its upper end adapted to be engaged by alaterally extending bracket 40 mounted on and movable with ram 14. Rack34 meshes with a gear 42 on a stub shaft 44 in drive assembly 28 (FIG.4). Stub shaft 44 also carries a larger gear 46 which meshes withanother gear 48 at one end of a coupling shaft 50 extending betweendrive assembly 28 and tray assembly 30. A gear 52 at the other end ofshaft 50 meshes with a gear rack 54 secured to the lower side of aworkpiece-receiving tray 56 (FIG. 5 Tray 56 is supported on a bracket 58by means of four rollers 60 (two at each side of the tray) which engagewith guideways 62 fonned along each side of gear rack 54. Bracket 58 ispivotally supported at the axis of shaft 50 on a base 64. Suitable studsand nuts 66 on bracket 58 cooperate with arcuate slots 68 on base 64 foradjusting tray 56 to the inclination desired.

The apparatus thus far described is in general the same as thatdisclosed in my prior U.S. Pat. No. 3,148,571.

With the arrangement thus described it will be appreciated that inresponse to vertical reciprocation of rack 34 tray 56 is reciprocatedbetween the work-receiving position shown in FIG. 1 and the retractedposition shown in FIG. 2. The upward travel of rack 34 causes tray 56 tomove from the retracted position to the work-receiving position; thedownward travel of the rack causes the tray to move from thework-receiving position to the retracted position. In the work-receivingposition the upper end of tray 56 is located to receive workpieces 70ejected from upper die 18. In the retracted position the upper end oftray 56 is disposed out of the path of travel of die 18 so as not tointerfere therewith.

As shown in FIGS. 1 and 2 the lower end of rack 34 is coupled to theupper external end of a cylinder rod 72. The cylinder 74 associated withrod 72 is mounted on support bracket 26 by a depending bracket structure76. The lower internal end of cylinder rod 72 is attached to a piston 78which is adapted to reciprocate within cylinder 74. Cylinder 74 and rod72 are vertically aligned with rack 34. Cylinder 74 has an upper port 80and a lower port 82 through which pressure fluid is introduced to causereciprocation of piston 78. The introduction of pressure fluid into thecylinder through port 80 causes piston 78 to travel downwardly while theintroduction of pressure fluid into the cylinder through port 82 causesthe piston to move upwardly. Thus it will be appreciated that theintroduction of pressure fluid into cylinder 74 through port 82 causestray 56 to be shifted toward the work-receiving position shown inFIG. 1. Similarly, the introduction of pressure fluid into cylinder 74through port 80 causes tray 56 to be shifted toward the retractedposition shown in FIG. 2.

FIG. 6 schematically shows the means for introducing pressure fluid intocylinder 74. A source of pressure fluid 84 is conducted to atwo-position directional valve 86. With valve 86 in the position shown,pressure fluid is introduced into cylinder 74 through port 80. Withvalve 86 in the other position, pressure fluid is introduced into thecylinder through port 82.

Valve 86 is pilot operated by cam actuated valves 88, 90. Valves 88, areidentical two-position valves, to which pressure fluid is conducteddirectly from source 84. With valve 90 in the actuated position shown inFIG. 6, pressure fluid is conducted through it to an adjustable delayvalve 92, which delays the flow of pressure fluid for a preselectedinterval, and then to one end of valve 86. This causes valve 86 toassume the position shown in FIG. 6. When valve 88 is actuated, pressurefluid is conducted through it directly to the opposite end of valve 86.This causes valve 86 to assume the other position.

Valve 88 is actuated when ram 14 is adjacent the lower end of its strokethereby shifting tray 56 away from the retracted position toward thework-receiving position. Since the upward travel of rack 34 is limitedby the contact of bumper 38 with ram bracket 40 the upward rate of therack equals the upward rate of the ram. Thus, tray 56 is shifted to thework-receiving position at a rate proportional to the rate of the upwardtravel of the ram.

Valve 90 is actuated when ram 14 is adjacent the upper end of its strokethereby shifting tray 56 away from the workreceiving position toward theretracted position. With rack 34 free to move downwardly, tray 56 isretracted at a relatively rapid rate independent of the rate of travelof the ram.

The significance of the present invention can be more fully appreciatedby the following description of an operating cycle.

With ram 14 traveling downward tray 56 is located at the retractedposition. As the ram reaches the lower end of its stroke, therebybringing upper die 18 into engagement with lower die 20, valve 88 isactuated by ram bracket 40. This causes pressure fluid to be introducedinto cylinder 74 through port 82, and rack 34 begins to travel upward.Since there will usually be a small gap between bumper element 38 andram bracket 40 as the ram comes to the lower end of its stroke, anadjustable flow control valve 94 is placed in the connection betweenport 82 and valve 86. By limiting the flow of pressure fluid intocylinder 74, the impact of rack 34 on ram bracket 40 is therebycushioned. However, the supply of pressure fluid into the cylinder issufficient to maintain the contact of rack 34 against bracket 40 as theram rises. Thus tray 56 shifts from the retracted to the work-receivingposition at a rate proportional to the speed of the ram on its upstroke.

As ram 14 reaches the upper end of its stroke tray 56 is disposedbeneath upper die 18 at the work-receiving position. At the same timevalve 90 is actuated by ram bracket 40. Delay valve 92 is adjusted suchthat workpieces are ejected onto tray 56 before the signal from valve 90is allowedto shift valve 86 to the position shown in FIG. 6. After valve86 has been shifted by valve 90, pressure fluid is introduced intocylinder 74 through port 80 and tray 56 retracts rapidly while ram 14remains at the upper end of its stroke after having completed its cycle.If desired, the rate of tray retraction may be controlled by a flowcontrol valve 96 inserted between valve 86 and port 80..Once tray 56 isin the retracted position it will remain there until valve 88 is againactuated by ram 14.

Thus, because of the operative coupling between tray 56 and ram 14during the press upstroke, the tray will always be shifted to itswork-receiving position with maximum speed and positive accuracy.Because this operative connection is broken after the press ram reachesthe upper end of its stroke,

the tray may be rapidly retracted independent of the press ram position.This leaves the space between the upper and lower dies free and clearfor the loading of the next workpiece.

I claim:

1. In combination a press having a vertically reciprocating ram on whichan upper die is adapted to be mounted for cooperation with a lower diemounted on the bed of the press, a press unloader for receivingworkpieces ejected from the upper die when the dies are verticallyseparated, said unloader comprising a tray shiftable from awork-receiving position disposed between the vertically separated upperand lower dies to a retracted position out of the path of travel of theupper die, means operative with the upward movement of the press ram andmovable at a rate determined bythe upward rate and movable at a ratedetermined by the upward rate of travel of the press ram for shiftingsaid tray from said retracted position to said work-receiving position,means for retracting the tray at a rate of travel greater than said rateof tray travel during shifting to the work-receiving position, and meansfor actuating the tray retracting means when the ram reaches apredetermined position.

2. The combination set forth in claim 1 wherein said means for shiftingthe tray from the retracted position to the workreceiving position isadapted to move the tray at a rate proportional to the rate of travel ofthe ram on its upward stroke.

3. The combination set forth in claim 1 wherein said means for shiftingthe tray from the retracted position to the workreceiving positioncomprises a vertically reciprocating shaft.

4. The combination set forth in claim 3 including means forinterengaging said shaft and the ram on the upstroke of the ram.

5. The combination set forth in claim 4 wherein said lastmentioned meansincludes a fluid cylinder having a piston operatively connected withsaid shaft.

6. The combination set forth in claim 5 wherein the piston is adapted toshift said shaft vertically in opposite directions in response toapplication of fluid pressure to opposite sides thereof.

7. The combination set forth in claim 6 wherein said means for shiftingthe tray to the work-receiving position comprises abutment means locatedbetween said ram and the upper end portion of said shaft and valve meansfor directing pressure fluid to one side of the piston for interengagingsaid abutment means on the upward stroke of the ram for causing saidtray to shift from said retracted position to said work-receivingposition at a rate controlled by the upward rate of travel of the ram.

8. The combination set forth in claim 7 wherein said means forretracting said tray includes said cylinder and said means for actuatingthe tray retracting means includes valve means which when actuated isadapted to apply pressure fluid to the opposite side of the piston fordisplacing said shaft downwardly at a rate in excess of the rate oftravel of the ram on its downward stroke.

9. The combination set forth in claim 8 including an actuator for saidlast-mentioned valve means, said actuator being disposed so as to betripped by the ram when the ram reaches a predetermined position.

10. The combination set forth in claim 1 wherein said predeterminedposition is adjacent the upper end of the ram stroke.

11. In combination a press having a vertically reciprocating ram onwhich an upper die element is adapted to be mounted for cooperation witha lower die mounted on the bed of the press, a press unloader forreceiving workpieces ejected from the upper die when the dies arevertically separated, said unloader comprising a tray shiftable from awork-receiving position disposed between the vertically separated upperand lower dies to a retracted position out of the path of travel of theupper die, means operative with the upward movement of the press ram forshifting the tray from said retracted position to said work-receivingposition at a rate of travel determined by the rate of travel of theram, means biasing the tray toward said retracted position forretracting the tray at a rate of travel greater than the rate at whichthe tray is shifted to the workreceiving position, and means forrendering said biasing means effective as the ram approaches the upperend of its stroke.

12. The combination set forth in claim 11 including means for renderingsaid biasing means ineffective as the ram approaches the lower end ofits stroke.

1. In combination a press having a vertically reciprocating ram on whichan upper die is adapted to be mounted for cooperation with a lower diemounted on the bed of the press, a press unloader for receivingworkpieces ejected from the upper die when the dies are verticallyseparated, said unloader comprising a tray shiftable from awork-receiving position disposed between the vertically separated upperand lower dies to a retracted position out of the path of travel of theupper die, means operative with the upward movement of the press ram andmovable aT a rate determined by the upward rate and movable at a ratedetermined by the upward rate of travel of the press ram for shiftingsaid tray from said retracted position to said workreceiving position,means for retracting the tray at a rate of travel greater than said rateof tray travel during shifting to the work-receiving position, and meansfor actuating the tray retracting means when the ram reaches apredetermined position.
 2. The combination set forth in claim 1 whereinsaid means for shifting the tray from the retracted position to thework-receiving position is adapted to move the tray at a rateproportional to the rate of travel of the ram on its upward stroke. 3.The combination set forth in claim 1 wherein said means for shifting thetray from the retracted position to the work-receiving positioncomprises a vertically reciprocating shaft.
 4. The combination set forthin claim 3 including means for interengaging said shaft and the ram onthe upstroke of the ram.
 5. The combination set forth in claim 4 whereinsaid last-mentioned means includes a fluid cylinder having a pistonoperatively connected with said shaft.
 6. The combination set forth inclaim 5 wherein the piston is adapted to shift said shaft vertically inopposite directions in response to application of fluid pressure toopposite sides thereof.
 7. The combination set forth in claim 6 whereinsaid means for shifting the tray to the work-receiving positioncomprises abutment means located between said ram and the upper endportion of said shaft and valve means for directing pressure fluid toone side of the piston for interengaging said abutment means on theupward stroke of the ram for causing said tray to shift from saidretracted position to said work-receiving position at a rate controlledby the upward rate of travel of the ram.
 8. The combination set forth inclaim 7 wherein said means for retracting said tray includes saidcylinder and said means for actuating the tray retracting means includesvalve means which when actuated is adapted to apply pressure fluid tothe opposite side of the piston for displacing said shaft downwardly ata rate in excess of the rate of travel of the ram on its downwardstroke.
 9. The combination set forth in claim 8 including an actuatorfor said last-mentioned valve means, said actuator being disposed so asto be tripped by the ram when the ram reaches a predetermined position.10. The combination set forth in claim 1 wherein said predeterminedposition is adjacent the upper end of the ram stroke.
 11. In combinationa press having a vertically reciprocating ram on which an upper dieelement is adapted to be mounted for cooperation with a lower diemounted on the bed of the press, a press unloader for receivingworkpieces ejected from the upper die when the dies are verticallyseparated, said unloader comprising a tray shiftable from awork-receiving position disposed between the vertically separated upperand lower dies to a retracted position out of the path of travel of theupper die, means operative with the upward movement of the press ram forshifting the tray from said retracted position to said work-receivingposition at a rate of travel determined by the rate of travel of theram, means biasing the tray toward said retracted position forretracting the tray at a rate of travel greater than the rate at whichthe tray is shifted to the work-receiving position, and means forrendering said biasing means effective as the ram approaches the upperend of its stroke.
 12. The combination set forth in claim 11 includingmeans for rendering said biasing means ineffective as the ram approachesthe lower end of its stroke.